Field of the Invention
The present disclosure relates to a method and apparatus for controlling luminance of an organic light emitting diode (OLED) display device and, more particularly, to a method and apparatus for controlling luminance of an OLED display device, which are capable of reducing power consumption caused by luminance improvement and outputting an image having high clarity and readability, by controlling luminance of the image in a manner of improving luminance of an achromatic color.
Discussion of the Related Art
An OLED display device is a self-emissive device in which light is emitted from an organic emission layer by recombination of electrons and holes and is expected to be a next-generation display device due to high luminance, low driving voltage, and ultra-thin thickness.
The OLED display device includes a plurality of pixels (subpixels), each of which includes an OLED element and a pixel circuit. The OLED element has an organic light emission layer disposed between an anode and a cathode, and the pixel circuit independently drives the OLED element. The pixel circuit includes a switching transistor, a storage capacitor, and a driving transistor. The switching transistor charges a voltage corresponding to a data signal in the storage capacitor in response to a scan pulse. The driving transistor controls current supplied to the OLED element according to the voltage charged in the storage capacitor to adjust the amount of light emitted from the OLED element. The amount of light emitted from the OLED element is proportional to current supplied by the driving transistor.
The OLED display device uses an RGBW type display device including a white (W) subpixel in addition to red (R), green (G), and blue (B) subpixels, in order to improve luminance and luminous efficiency while maintaining color reproduction. The RGBW OLED display device extracts a gain value using a gray level difference between R, G, and B data, and displays an image using a minimum value of the R, G, and B data as data of W pixel data.
For luminance improvement, such a conventional OLED display device uses a method for improving luminance of an entire display area. Then, power consumption increases due to driving of all subpixels for luminance improvement and thus efficiency degradation occurs, which leads to reduction in lifespan of the OLED element.
In addition, since the conventional OLED display device improves luminance of the entire display area, clarity and readability of a dark image or an image at an edge are degraded.